The present invention relates to a recombinant process for the production of truncated and/or mutated dextransucrases while conserving their enzymatic activity and/or conserving their specificity for synthesizing α-1,6 bonds. More precisely, the present invention relates to nucleic acid sequences of truncated or mutated dextransucrases, vectors containing said nucleic acid sequences and host cells transformed by sequences encoding truncated or mutated dextransucrases. In a further aspect, the invention concerns a method for producing, in a recombinant manner, truncated and/or mutated dextransucrases which conserve their enzymatic activity and/or conserve their specificity for synthesizing α-1,6 bonds in the final product and methods for producing dextrans or isomalto-oligosaccharides, in a single step, with a controlled molar mass and dextrans with modified rheological properties, especially compared with the properties of dextrans obtained with the native enzyme.